2. The Very High Level Layer

The functions in this chapter will let you execute Python source code
given in a file or a buffer, but they will not let you interact in a
more detailed way with the interpreter.

Several of these functions accept a start symbol from the grammar as a
parameter. The available start symbols are Py_eval_input,
Py_file_input, and Py_single_input. These are
described following the functions which accept them as parameters.

Note also that several of these functions take FILE*
parameters. On particular issue which needs to be handled carefully
is that the FILE structure for different C libraries can be
different and incompatible. Under Windows (at least), it is possible
for dynamically linked extensions to actually use different libraries,
so care should be taken that FILE* parameters are only passed
to these functions if it is certain that they were created by the same
library that the Python runtime is using.

int Py_Main(

int argc, char **argv)

The main program for the standard interpreter. This is made
available for programs which embed Python. The argc and
argv parameters should be prepared exactly as those which are
passed to a C program's main() function. It is
important to note that the argument list may be modified (but the
contents of the strings pointed to by the argument list are not).
The return value will be the integer passed to the
sys.exit() function, 1 if the interpreter exits
due to an exception, or 2 if the parameter list does not
represent a valid Python command line.

int PyRun_AnyFile(

FILE *fp, const char *filename)

This is a simplified interface to PyRun_AnyFileExFlags()
below, leaving closeit set to 0 and flags set to NULL.

int PyRun_AnyFileFlags(

FILE *fp, const char *filename,
PyCompilerFlags *flags)

This is a simplified interface to PyRun_AnyFileExFlags()
below, leaving the closeit argument set to 0.

int PyRun_AnyFileEx(

FILE *fp, const char *filename,
int closeit)

This is a simplified interface to PyRun_AnyFileExFlags()
below, leaving the flags argument set to NULL.

int PyRun_AnyFileExFlags(

FILE *fp, const char *filename,
int closeit,
PyCompilerFlags *flags)

If fp refers to a file associated with an interactive device
(console or terminal input or Unix pseudo-terminal), return the
value of PyRun_InteractiveLoop(), otherwise return the
result of PyRun_SimpleFile(). If filename is
NULL, this function uses "???" as the filename.

int PyRun_SimpleString(

const char *command)

This is a simplified interface to PyRun_SimpleStringFlags()
below, leaving the PyCompilerFlags* argument set to NULL.

int PyRun_SimpleStringFlags(

const char *command,
PyCompilerFlags *flags)

Executes the Python source code from command in the
__main__ module according to the flags argument.
If __main__ does not already exist, it is created. Returns
0 on success or -1 if an exception was raised. If there
was an error, there is no way to get the exception information.
For the meaning of flags, see below.

int PyRun_SimpleFile(

FILE *fp, const char *filename)

This is a simplified interface to PyRun_SimpleFileExFlags()
below, leaving closeit set to 0 and flags set to
NULL.

int PyRun_SimpleFileFlags(

FILE *fp, const char *filename,
PyCompilerFlags *flags)

This is a simplified interface to PyRun_SimpleFileExFlags()
below, leaving closeit set to 0.

int PyRun_SimpleFileEx(

FILE *fp, const char *filename,
int closeit)

This is a simplified interface to PyRun_SimpleFileExFlags()
below, leaving flags set to NULL.

int PyRun_SimpleFileExFlags(

FILE *fp, const char *filename,
int closeit,
PyCompilerFlags *flags)

Similar to PyRun_SimpleStringFlags(), but the Python source
code is read from fp instead of an in-memory string.
filename should be the name of the file. If closeit is
true, the file is closed before PyRun_SimpleFileExFlags returns.

int PyRun_InteractiveOne(

FILE *fp, const char *filename)

This is a simplified interface to PyRun_InteractiveOneFlags()
below, leaving flags set to NULL.

int PyRun_InteractiveOneFlags(

FILE *fp,
const char *filename,
PyCompilerFlags *flags)

Read and execute a single statement from a file associated with an
interactive device according to the flags argument. If
filename is NULL, "???" is used instead. The user will
be prompted using sys.ps1 and sys.ps2. Returns 0
when the input was executed successfully, -1 if there was an
exception, or an error code from the errcode.h include file
distributed as part of Python if there was a parse error. (Note that
errcode.h is not included by Python.h, so must be included
specifically if needed.)

int PyRun_InteractiveLoop(

FILE *fp, const char *filename)

This is a simplified interface to PyRun_InteractiveLoopFlags()
below, leaving flags set to NULL.

int PyRun_InteractiveLoopFlags(

FILE *fp,
const char *filename,
PyCompilerFlags *flags)

Read and execute statements from a file associated with an
interactive device until EOF is reached. If filename is
NULL, "???" is used instead. The user will be prompted
using sys.ps1 and sys.ps2. Returns 0 at EOF.

struct _node* PyParser_SimpleParseString(

const char *str,
int start)

This is a simplified interface to
PyParser_SimpleParseStringFlagsFilename() below, leaving
filename set to NULL and flags set to 0.

struct _node* PyParser_SimpleParseStringFlags(

const char *str, int start, int flags)

This is a simplified interface to
PyParser_SimpleParseStringFlagsFilename() below, leaving
filename set to NULL.

struct _node* PyParser_SimpleParseStringFlagsFilename(

const char *str, const char *filename,
int start, int flags)

Parse Python source code from str using the start token
start according to the flags argument. The result can
be used to create a code object which can be evaluated efficiently.
This is useful if a code fragment must be evaluated many times.

struct _node* PyParser_SimpleParseFile(

FILE *fp,
const char *filename, int start)

This is a simplified interface to PyParser_SimpleParseFileFlags()
below, leaving flags set to 0

struct _node* PyParser_SimpleParseFileFlags(

FILE *fp,
const char *filename, int start, int flags)

Similar to PyParser_SimpleParseStringFlagsFilename(), but
the Python source code is read from fp instead of an in-memory
string.

PyObject* PyRun_String(

const char *str, int start,
PyObject *globals,
PyObject *locals)

Return value:New reference.

This is a simplified interface to PyRun_StringFlags() below,
leaving flags set to NULL.

Execute Python source code from str in the context specified
by the dictionaries globals and locals with the compiler
flags specified by flags. The parameter start specifies
the start token that should be used to parse the source code.

Returns the result of executing the code as a Python object, or
NULL if an exception was raised.

Similar to PyRun_StringFlags(), but the Python source code is
read from fp instead of an in-memory string.
filename should be the name of the file.
If closeit is true, the file is closed before
PyRun_FileExFlags() returns.

PyObject* Py_CompileString(

const char *str,
const char *filename,
int start)

Return value:New reference.

This is a simplified interface to Py_CompileStringFlags() below,
leaving flags set to NULL.

Parse and compile the Python source code in str, returning the
resulting code object. The start token is given by start;
this can be used to constrain the code which can be compiled and should
be Py_eval_input, Py_file_input, or
Py_single_input. The filename specified by
filename is used to construct the code object and may appear
in tracebacks or SyntaxError exception messages. This
returns NULL if the code cannot be parsed or compiled.

int Py_eval_input

The start symbol from the Python grammar for isolated expressions;
for use with
Py_CompileString().

int Py_file_input

The start symbol from the Python grammar for sequences of statements
as read from a file or other source; for use with
Py_CompileString(). This is
the symbol to use when compiling arbitrarily long Python source code.

int Py_single_input

The start symbol from the Python grammar for a single statement; for
use with Py_CompileString().
This is the symbol used for the interactive interpreter loop.

This is the structure used to hold compiler flags. In cases where
code is only being compiled, it is passed as int flags, and in
cases where code is being executed, it is passed as
PyCompilerFlags *flags. In this case, from __future__
import can modify flags.

Whenever PyCompilerFlags *flags is NULL, cf_flags
is treated as equal to 0, and any modification due to
from __future__ import is discarded.

struct PyCompilerFlags {
int cf_flags;
}

int CO_FUTURE_DIVISION

This bit can be set in flags to cause division operator /
to be interpreted as ``true division'' according to PEP 238.